CN116904750A - Method for step recovery of lithium and rare earth from rare earth molten salt electrolysis slag - Google Patents
Method for step recovery of lithium and rare earth from rare earth molten salt electrolysis slag Download PDFInfo
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- CN116904750A CN116904750A CN202310894758.3A CN202310894758A CN116904750A CN 116904750 A CN116904750 A CN 116904750A CN 202310894758 A CN202310894758 A CN 202310894758A CN 116904750 A CN116904750 A CN 116904750A
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- 229910052761 rare earth metal Inorganic materials 0.000 title claims abstract description 137
- 150000002910 rare earth metals Chemical class 0.000 title claims abstract description 114
- 239000002893 slag Substances 0.000 title claims abstract description 96
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 68
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 68
- 150000003839 salts Chemical class 0.000 title claims abstract description 53
- 238000000034 method Methods 0.000 title claims abstract description 49
- 238000005868 electrolysis reaction Methods 0.000 title claims abstract description 40
- 238000011084 recovery Methods 0.000 title claims description 14
- 238000002386 leaching Methods 0.000 claims abstract description 145
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 44
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 33
- 239000002253 acid Substances 0.000 claims abstract description 32
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical group O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 claims abstract description 23
- 239000000654 additive Substances 0.000 claims abstract description 18
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 17
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 17
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 17
- 230000009466 transformation Effects 0.000 claims abstract description 16
- 229910052731 fluorine Inorganic materials 0.000 claims abstract description 15
- 239000011737 fluorine Substances 0.000 claims abstract description 15
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims abstract description 12
- 230000000996 additive effect Effects 0.000 claims abstract description 12
- 239000007788 liquid Substances 0.000 claims abstract description 12
- 239000003513 alkali Substances 0.000 claims abstract description 10
- 238000006243 chemical reaction Methods 0.000 claims description 25
- 230000008569 process Effects 0.000 claims description 16
- 239000007787 solid Substances 0.000 claims description 16
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims description 14
- 230000035484 reaction time Effects 0.000 claims description 12
- 239000003792 electrolyte Substances 0.000 claims 8
- 238000004064 recycling Methods 0.000 abstract description 10
- 238000000605 extraction Methods 0.000 abstract description 5
- 238000000926 separation method Methods 0.000 abstract description 2
- 239000002699 waste material Substances 0.000 abstract description 2
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 abstract 1
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 24
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 18
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 14
- -1 rare earth fluoride Chemical class 0.000 description 13
- 239000002994 raw material Substances 0.000 description 8
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 7
- 229910052808 lithium carbonate Inorganic materials 0.000 description 7
- 238000007873 sieving Methods 0.000 description 7
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 5
- 150000004673 fluoride salts Chemical class 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- PUZPDOWCWNUUKD-UHFFFAOYSA-M sodium fluoride Chemical compound [F-].[Na+] PUZPDOWCWNUUKD-UHFFFAOYSA-M 0.000 description 4
- 239000000463 material Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229910052684 Cerium Inorganic materials 0.000 description 2
- 229910052777 Praseodymium Inorganic materials 0.000 description 2
- 229910052771 Terbium Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 2
- PQXKHYXIUOZZFA-UHFFFAOYSA-M lithium fluoride Chemical compound [Li+].[F-] PQXKHYXIUOZZFA-UHFFFAOYSA-M 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- PUDIUYLPXJFUGB-UHFFFAOYSA-N praseodymium atom Chemical compound [Pr] PUDIUYLPXJFUGB-UHFFFAOYSA-N 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000011775 sodium fluoride Substances 0.000 description 2
- 235000013024 sodium fluoride Nutrition 0.000 description 2
- GZCRRIHWUXGPOV-UHFFFAOYSA-N terbium atom Chemical compound [Tb] GZCRRIHWUXGPOV-UHFFFAOYSA-N 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 150000002222 fluorine compounds Chemical group 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- INHCSSUBVCNVSK-UHFFFAOYSA-L lithium sulfate Inorganic materials [Li+].[Li+].[O-]S([O-])(=O)=O INHCSSUBVCNVSK-UHFFFAOYSA-L 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- RBTVSNLYYIMMKS-UHFFFAOYSA-N tert-butyl 3-aminoazetidine-1-carboxylate;hydrochloride Chemical compound Cl.CC(C)(C)OC(=O)N1CC(N)C1 RBTVSNLYYIMMKS-UHFFFAOYSA-N 0.000 description 1
- 230000001131 transforming effect Effects 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/006—Wet processes
- C22B7/007—Wet processes by acid leaching
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D15/00—Lithium compounds
- C01D15/08—Carbonates; Bicarbonates
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/02—Roasting processes
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B26/00—Obtaining alkali, alkaline earth metals or magnesium
- C22B26/10—Obtaining alkali metals
- C22B26/12—Obtaining lithium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B59/00—Obtaining rare earth metals
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Geology (AREA)
- Manufacturing & Machinery (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Environmental & Geological Engineering (AREA)
- Geochemistry & Mineralogy (AREA)
- Inorganic Chemistry (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
The application provides a method for recycling lithium and rare earth from rare earth molten salt electrolysis slag in a gradient manner, and belongs to the technical field of metallurgical waste residue treatment and secondary resource recycling. The method comprises the following steps: (1) Leaching the rare earth molten salt electrolysis slag by reacting with sulfuric acid to obtain a lithium-containing solution and leaching slag; (2) Mixing leaching residues with additives, and performing low-temperature roasting transformation to obtain a roasting product; (3) Leaching the roasting product by water to obtain leaching slag; (4) Acid leaching is carried out on the water leaching slag, and a reducing agent is added to obtain rare earth leaching liquid and leaching slag; wherein the additive is alkali and active carbon, and the reducing agent is formaldehyde or hydrogen peroxide. The method provided by the application realizes ore phase transformation and efficient extraction of lithium and rare earth in the rare earth molten salt electrolytic slag, realizes separation of lithium and rare earth, can recover fluorine, and has the advantages of high extraction rate of lithium and rare earth, greenness and the like.
Description
Technical Field
The application belongs to the technical field of metallurgical waste residue treatment and secondary resource recycling, and particularly relates to a method for recycling lithium and rare earth from rare earth molten salt electrolysis residues in a gradient manner.
Background
China is the largest rare earth producing country in the world and occupies more than 70% of the world output. At present, the main methods for preparing rare earth metals are metal thermal reduction and molten salt electrolysis, and fluoride system electrolysis is the most common molten salt electrolysis. According to estimation, the rare earth molten salt electrolysis slag generated in the molten salt electrolysis process is about 5% of the metal amount, the rare earth molten salt electrolysis slag contains lithium and rare earth, the contents of which are respectively 1-6% and 40-80% are different, and the contents of the rare earth molten salt electrolysis slag are greatly higher than the grade in raw ore, so that the rare earth molten salt electrolysis slag has very high recycling value; however, the components are complex, and the main existing phase is fluoride, so that the rare earth is difficult to extract efficiently. At present, the recycling method is mainly concentrated in the extraction of rare earth by an acid method and an alkali method, the leaching rate of part of rare earth is low, only part of rare earth can be extracted, and less attention is paid to lithium. Therefore, how to realize the efficient and comprehensive recovery of rare earth and lithium in the rare earth molten salt electrolysis slag is a difficult problem to be solved urgently.
Disclosure of Invention
In order to solve the technical problems, the application provides a method for recovering lithium and rare earth from rare earth molten salt electrolysis slag in a gradient way.
The application provides a method for recovering lithium and rare earth from rare earth molten salt electrolysis slag in a gradient way, which comprises the following steps:
(1) Leaching the rare earth molten salt electrolysis slag by sulfuric acid to obtain a lithium-containing solution and leached slag, wherein the lithium-containing solution is used for recovering lithium, and the lithium-containing solution can be used as a raw material for preparing lithium carbonate; the reaction equation involved in this step is:
2LiF+H 2 SO 4 ＝Li 2 SO 4 +2HF
Li 2 SO 4 +CO 3 2- ＝Li 2 CO 3 +SO 4 2-
(2) Mixing the leaching residue with an additive, and performing low-temperature transformation roasting to obtain a roasting product, wherein the additive is alkali and active carbon, and the alkali is sodium hydroxide or potassium hydroxide; the reaction equation involved in this step is as follows, where RE is a rare earth element:
REF 3 +3OH - ＝RE(OH) 3 +3F -
REF 4 +4OH - ＝RE(OH) 4 +4F -
4RE(OH) 4 +C＝4RE(OH) 3 +2H 2 O↑+CO 2 ↑
(3) Crushing the roasting product obtained in the step (2), sieving with a 100-mesh sieve, and adding water for leaching to obtain water leaching slag and fluorine-containing solution; (4) And (3) acid leaching the water leaching slag by using hydrochloric acid or sulfuric acid, and adding a reducing agent in the acid leaching process to obtain rare earth leaching liquid and leaching slag, so as to realize recovery of rare earth, wherein the reducing agent is formaldehyde and/or hydrogen peroxide. The reaction equation involved in this step is:
2RE(OH) 4 +H 2 O 2 ＝4RE(OH) 3 +H 2 O+O 2 ↑
4RE(OH) 4 +HCHO＝4RE(OH) 3 +3H 2 O+CO 2 ↑
RE(OH) 3 +3H + ＝RE 3+ +H 2 O
furthermore, the application does not limit the source of the rare earth molten salt electrolysis slag, so long as the rare earth molten salt electrolysis slag is produced by adopting a fluoride salt system to prepare single rare earth metal or alloy through molten salt electrolysis, but has more obvious effects on the rare earth elements such as terbium, cerium, praseodymium and the like containing variable valence rare earth elements, the total content of the rare earth elements in the rare earth molten salt electrolysis slag is 20-80%, the total content of lithium is 1-6%, and the rare earth elements and the lithium are mainly fluoride.
Further, in the step (1), the mass fraction of the sulfuric acid is 70% -98%, and the liquid-solid ratio of the sulfuric acid to the rare earth molten salt electrolysis slag is 3:1-10:1.
Further, in the step (1), the reaction temperature of leaching is 30-95 ℃ and the reaction time is 1-30 h.
Further, in the step (2), the amount of alkali in the additive is 1-1.5 times of the mass of the leaching slag, and the amount of carbon is 0-8% of the mass of the leaching slag (dry basis).
Further, in the step (2), the reaction temperature of the low-temperature transformation roasting is 100-700 ℃ and the reaction time is 0.5-6 h.
Further, in the step (3), the liquid-solid ratio of the roasting product to water is 3:1-10:1.
Further, in the step (3), the reaction temperature of water adding leaching is 30-95 ℃ and the reaction time is 0.5-6 h.
Further, in the step (4), the mass ratio of the reducing agent to the acid leaching slag is 0.01-0.15:1, the acid leaching slag is leached by hydrochloric acid or sulfuric acid, and the final acidity of the acid leaching process is controlled to be 0.5mol/L.
Further, in the step (4), the reaction temperature of the acid leaching is 30-95 ℃ and the reaction time is 0.5-6 h.
Compared with the prior art, the application has the following advantages and technical effects:
the method of the application realizes the ore phase transformation (namely, the transformation of lithium fluoride into lithium sulfate) and the efficient extraction of lithium and rare earth in the rare earth molten salt electrolysis slag, and the method changes rare earth fluoride into rare earth hydroxide and fluorine into soluble fluoride through preferential acid leaching and transformation by low-temperature carbothermal reduction roasting, adopts a water leaching mode, and the fluorine is dissolved, and the rare earth is remained in the slag, thereby realizing the efficient separation of rare earth elements and fluorine, and simultaneously recycling the fluorine, and having the advantages of high extraction rate of lithium and rare earth, environmental protection and the like.
Detailed Description
Various exemplary embodiments of the application will now be described in detail, which should not be considered as limiting the application, but rather as more detailed descriptions of certain aspects, features and embodiments of the application.
It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. In addition, for numerical ranges in this disclosure, it is understood that each intermediate value between the upper and lower limits of the ranges is also specifically disclosed. Every smaller range between any stated value or stated range, and any other stated value or intermediate value within the stated range, is also encompassed within the application. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned in this specification are incorporated by reference for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.
It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the application described herein without departing from the scope or spirit of the application. Other embodiments will be apparent to those skilled in the art from consideration of the specification of the present application. The specification and examples of the present application are exemplary only.
As used herein, the terms "comprising," "including," "having," "containing," and the like are intended to be inclusive and mean an inclusion, but not limited to.
The application provides a method for recovering lithium and rare earth from rare earth molten salt electrolysis slag in a gradient way, which comprises the following steps:
(1) Leaching the rare earth molten salt electrolysis slag by sulfuric acid to obtain a lithium-containing solution and leached slag, wherein the lithium-containing solution is used for recovering lithium, and the lithium-containing solution can be used as a raw material for preparing lithium carbonate; the reaction equation involved in this step is:
2LiF+H 2 SO 4 ＝Li 2 SO 4 +2HF
Li 2 SO 4 +CO 3 2- ＝Li 2 CO 3 +SO 4 2-
(2) Mixing the leaching residue with an additive, and performing low-temperature transformation roasting to obtain a roasting product, wherein the additive is alkali and active carbon, and the alkali is sodium hydroxide or potassium hydroxide; the reaction equation involved in this step is as follows, where RE is a rare earth element:
REF 3 +3OH-＝RE(OH) 3 +3F-
REF 4 +4OH-＝RE(OH) 4 +4F-
4RE(OH) 4 +C＝4RE(OH) 3 +2H 2 O↑+CO 2 ↑
(3) Crushing the roasting product obtained in the step (2), sieving with a 100-mesh sieve, and adding water for leaching to obtain water leaching slag and fluorine-containing solution;
(4) And (3) carrying out acid leaching on the water leaching slag by using hydrochloric acid or sulfuric acid, wherein a reducing agent is added in the acid leaching process to obtain rare earth leaching liquid and leaching slag, recycling the rare earth from the leaching liquid, wherein the recycling process is a conventional technical means in the field, and the reducing agent is formaldehyde and/or hydrogen peroxide. The reaction equation involved in this step is:
2RE(OH) 4 +H 2 O 2 ＝4RE(OH) 3 +H 2 O+O 2 ↑
4RE(OH) 4 +HCHO＝4RE(OH) 3 +3H 2 O+CO 2 ↑
RE(OH) 3 +3H + ＝RE 3+ +H 2 O
the application does not limit the source of the rare earth molten salt electrolytic slag, but only needs to prepare the rare earth molten salt electrolytic slag generated by single rare earth metal or alloy by adopting a fluoride salt system for molten salt electrolysis, but has more obvious effects on the rare earth elements with variable valence such as terbium, cerium, praseodymium and the like.
In the step (1) of the embodiment of the application, the mass fraction of the sulfuric acid is 70% -98%, and the liquid-solid ratio of the sulfuric acid to the rare earth molten salt electrolysis slag is 3:1-10:1.
In the process of leaching the rare earth molten salt electrolysis slag by sulfuric acid, the leaching temperature is related to the lithium leaching rate, and in order to obtain higher leaching rate, in the step (1) of the embodiment of the application, the leaching reaction temperature is 30-95 ℃ and the reaction time is 1-30 h.
The additive has the function of reducing +4-valent rare earth to +3-valent rare earth, so in the step (2) of the embodiment of the application, a proper amount of additive is added, wherein the dosage of alkali in the additive is 1-1.5 times of the leaching slag mass, and the dosage of carbon is 0-8% of the leaching slag mass.
The transformation roasting at low temperature has the effect of transforming the rare earth fluoride into the rare earth hydroxide, the hardening is seriously unfavorable for the subsequent rare earth leaching due to the over high temperature, and the rare earth is not transformed due to the over low temperature. Based on the above, in the step (2) of the embodiment of the application, the reaction temperature of the low-temperature transformation roasting is 100-700 ℃ and the reaction time is 0.5-6 h.
In the step (3) of the embodiment of the application, the liquid-solid ratio of the roasting product to water is 3:1-10:1.
The water adding leaching process of the roasting product is to remove fluorine, dissolve the generated sodium fluoride, and the control of the leaching reaction temperature and time is favorable for dissolving the sodium fluoride. Therefore, in the step (3) of the embodiment of the application, the reaction temperature of the water adding leaching is 30-95 ℃ and the reaction time is 0.5-6 h.
The reducing agent is used for reducing +4-valent rare earth into +3-valent rare earth, in the step (4) of the embodiment of the application, the mass ratio of the reducing agent to acid leaching slag is 0.01-0.15:1, the acid leaching slag is leached by hydrochloric acid or sulfuric acid, and the final acidity of the acid leaching process is controlled to be 0.5mol/L, so that impurities are removed but the rare earth is not precipitated.
Leaching the water leaching slag again to leach the rare earth hydroxide into the solution, thereby achieving the purpose of recovering the rare earth, wherein in the step (4) of the embodiment of the application, the reaction temperature of the acid leaching is 30-95 ℃ and the reaction time is 0.5-6 h.
The raw materials used in the embodiment of the application are commercially available.
The technical scheme of the application is further described by the following examples.
Example 1
A method for recovering lithium and rare earth from rare earth molten salt electrolysis slag in a stepped manner comprises the following steps:
(1) Mixing rare earth molten salt electrolysis slag and sulfuric acid with the mass fraction of 90% according to the liquid-solid ratio of 6:1, and leaching at 80 ℃ for 10 hours to obtain a lithium-containing solution and leaching slag, so as to realize recovery of lithium, wherein the lithium-containing solution can be used as a raw material for preparing lithium carbonate, and the leaching rate of the lithium (namely the lithium content in the lithium-containing solution) reaches 75.98%;
(2) Mixing leaching slag with additives (sodium hydroxide and active carbon), wherein the dosage of sodium hydroxide is 1 time of the mass of the leaching slag, the dosage of carbon is 4% of the mass of the leaching slag (dry basis), and carrying out low-temperature transformation roasting for 2 hours at 400 ℃ to obtain a roasting product containing rare earth hydroxide and soluble fluoride salt;
(3) Crushing the roasting product, sieving the crushed roasting product with a 100-mesh sieve, adding water to remove fluorine according to a liquid-solid ratio of 5:1, and leaching the mixture at 60 ℃ for 2 hours to obtain water leaching slag (mainly rare earth hydroxide) and fluorine-containing solution;
(4) Mixing the water leaching slag with hydrochloric acid, performing acid leaching reaction for 3 hours at 75 ℃, adding a reducing agent (formaldehyde) in the acid leaching process, controlling the final acidity in the acid leaching process to be 0.5mol/L, obtaining rare earth leaching liquid and leaching slag, and recycling rare earth from the leaching liquid, wherein the rare earth leaching rate is more than 90.55%.
Example 2
A method for recovering lithium and rare earth from rare earth molten salt electrolysis slag in a stepped manner comprises the following steps:
(1) Mixing rare earth molten salt electrolysis slag with sulfuric acid with the mass fraction of 98% according to the liquid-solid ratio of 8:1, and leaching at 90 ℃ for 20 hours to obtain a lithium-containing solution and leaching slag, so as to realize the recovery of lithium, wherein the lithium-containing solution can be used as a raw material for preparing lithium carbonate, and the leaching rate of the lithium reaches 98.20%;
(2) Mixing leaching residues with additives (sodium hydroxide and active carbon), wherein the dosage of sodium hydroxide is 1.4 times of the mass of the leaching residues, the dosage of carbon is 6% of the mass of the leaching residues (dry basis), and carrying out low-temperature transformation roasting for 4 hours at 500 ℃ to obtain a roasting product containing rare earth hydroxide and soluble fluoride;
(3) Crushing the roasting product, sieving the crushed roasting product with a 100-mesh sieve, adding water according to a liquid-solid ratio of 10:1, and leaching the mixture at 90 ℃ for 4 hours to obtain water leaching slag (mainly rare earth hydroxide) and fluorine-containing solution;
(4) Mixing the water leaching slag with hydrochloric acid, performing acid leaching reaction for 4 hours at 90 ℃, adding a reducing agent (hydrogen peroxide) in the acid leaching process, controlling the final acidity to be 0.5mol/L, and obtaining rare earth leaching liquid and leaching slag, wherein the rare earth element is recovered from the rare earth leaching liquid, and the rare earth leaching rate is more than 98.68%.
Example 3
A method for recovering lithium and rare earth from rare earth molten salt electrolysis slag in a stepped manner comprises the following steps:
(1) Mixing rare earth molten salt electrolysis slag with sulfuric acid with the mass fraction of 98% according to the liquid-solid ratio of 6:1, and leaching at 70 ℃ for 15 hours to obtain a lithium-containing solution and leaching slag, so as to realize the recovery of lithium, wherein the lithium-containing solution can be used as a raw material for preparing lithium carbonate, and the leaching rate of the lithium reaches 96.52%;
(2) Mixing leaching residue with additives (potassium hydroxide and active carbon), wherein the dosage of potassium hydroxide is 1.2 times of the mass of leaching residue, the dosage of carbon is 5% of the mass of leaching residue (dry basis), and carrying out low-temperature conversion roasting for 3 hours at 600 ℃ to obtain a roasting product containing rare earth hydroxide and soluble fluoride;
(3) Crushing the roasting product, sieving the crushed roasting product with a 100-mesh sieve, adding water according to a liquid-solid ratio of 10:1, and leaching the mixture at 90 ℃ for 4 hours to obtain water leaching slag (mainly rare earth hydroxide) and fluorine-containing solution;
(4) Mixing the leaching residue with sulfuric acid, performing acid leaching reaction for 3 hours at 80 ℃, adding a reducing agent (formaldehyde) in the acid leaching process, controlling the final acidity to be 0.5mol/L, and obtaining rare earth leaching liquid and leaching residue, thereby realizing recovery of rare earth, and the rare earth leaching rate reaches more than 95.88%.
Example 4
A method for recovering lithium and rare earth from rare earth molten salt electrolysis slag in a stepped manner comprises the following steps:
(1) Mixing rare earth molten salt electrolysis slag and sulfuric acid with the mass fraction of 70% according to the liquid-solid ratio of 3:1, and leaching at 95 ℃ for 1h to obtain a lithium-containing solution and leaching slag, so as to realize the recovery of lithium, wherein the lithium-containing solution can be used as a raw material for preparing lithium carbonate, and the leaching rate of the lithium reaches 55.24%;
(2) Mixing leaching residues with additives (sodium hydroxide and active carbon), wherein the dosage of sodium hydroxide is 1 time of the mass of the leaching residues, the dosage of carbon is 8% of the mass of the leaching residues, and carrying out low-temperature transformation roasting for 6 hours at 100 ℃ to obtain a roasting product containing rare earth hydroxide and soluble fluoride salt;
(3) Crushing the roasting product, sieving the crushed roasting product with a 100-mesh sieve, adding water according to a liquid-solid ratio of 10:1, and leaching at 30 ℃ for 0.5h to obtain water leaching slag and fluorine-containing solution;
(4) Mixing the leaching residue with hydrochloric acid, performing acid leaching reaction for 6 hours at 30 ℃, adding a reducing agent (hydrogen peroxide) in the acid leaching process, controlling the final acidity to be 0.5mol/L, and obtaining rare earth leaching liquid and leaching residue, thereby realizing recovery of rare earth, and the rare earth leaching rate reaches more than 35.36%.
Example 5
A method for recovering lithium and rare earth from rare earth molten salt electrolysis slag in a stepped manner comprises the following steps:
(1) Mixing rare earth molten salt electrolysis slag and sulfuric acid with the mass fraction of 70% according to the liquid-solid ratio of 10:1, and leaching at 30 ℃ for 30 hours to obtain a lithium-containing solution and leaching slag, so as to realize the recovery of lithium, wherein the lithium-containing solution can be used as a raw material for preparing lithium carbonate, and the leaching rate of the lithium reaches 50.65%;
(2) Mixing leaching residue with additives (potassium hydroxide and active carbon), wherein the dosage of potassium hydroxide is 1.5 times of the mass of leaching residue, the dosage of carbon is 1% of the mass of leaching residue, and carrying out low-temperature transformation roasting for 0.5h at 700 ℃ to obtain a roasting product containing rare earth hydroxide and soluble fluoride salt;
(3) Crushing the roasting product, sieving the crushed roasting product with a 100-mesh sieve, adding water according to a liquid-solid ratio of 3:1, and leaching at 95 ℃ for 0.5h to obtain water leaching slag and fluorine-containing solution;
(4) Mixing the water leaching slag with sulfuric acid, carrying out acid leaching reaction for 0.5h at 95 ℃, adding a reducing agent (formaldehyde) in the acid leaching process, controlling the final acidity to be 0.5mol/L, and obtaining rare earth leaching liquid and leaching slag, thereby realizing the recovery of rare earth, and the rare earth leaching rate reaches more than 91.67%.
The present application is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present application are intended to be included in the scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.
Claims (10)
1. The method for step recovery of lithium and rare earth from rare earth molten salt electrolysis slag is characterized by comprising the following steps:
(1) Leaching the rare earth molten salt electrolysis slag by sulfuric acid to obtain a lithium-containing solution and leached slag, wherein the lithium-containing solution is used for recovering lithium;
(2) Mixing the leaching residue with an additive, and performing low-temperature transformation roasting to obtain a roasting product, wherein the additive is alkali and active carbon;
(3) Adding water to leach the roasting product to obtain water leaching slag and fluorine-containing solution;
(4) And (3) carrying out acid leaching on the water leaching slag, wherein a reducing agent is added in the acid leaching process to obtain rare earth leaching liquid and leaching slag, so that the recovery of rare earth is realized, and the reducing agent is formaldehyde and/or hydrogen peroxide.
2. The method for stepwise recovering lithium and rare earth from a rare earth molten salt electrolyte slag according to claim 1, wherein the total content of rare earth elements in the rare earth molten salt electrolyte slag is 20 to 80% and the total content of lithium is 1 to 6%.
3. The method for stepwise recovering lithium and rare earth from rare earth molten salt electrolytic slag according to claim 1, wherein in the step (1), the mass fraction of sulfuric acid is 70% -98%, and the liquid-solid ratio of sulfuric acid to rare earth molten salt electrolytic slag is 3:1-10:1.
4. The method for stepwise recovering lithium and rare earth from a rare earth molten salt electrolyte slag according to claim 1, wherein in the step (1), the reaction temperature of the leaching is 30 ℃ to 95 ℃ and the reaction time is 1h to 30h.
5. The method for stepwise recovering lithium and rare earth from a rare earth molten salt electrolyte slag as defined in claim 1, wherein in the step (2), the amount of alkali in the additive is 1.0 to 1.5 times the mass of the leaching slag, and the amount of carbon is 0 to 8% of the mass of the leaching slag.
6. The method for stepwise recovering lithium and rare earth from rare earth molten salt electrolyte slag as defined in claim 1, wherein in the step (2), the reaction temperature of the low-temperature transformation roasting is 100-700 ℃ and the reaction time is 0.5-6 h.
7. The method for stepwise recovering lithium and rare earth from a rare earth molten salt electrolyte slag as defined in claim 1, wherein in the step (3), the liquid-solid ratio of the calcined product to water is 3:1 to 10:1.
8. The method for stepwise recovering lithium and rare earth from molten salt electrolyte slag of claim 1, wherein in the step (3), the reaction temperature of water leaching is 30-95 ℃ and the reaction time is 0.5-6 h.
9. The method for stepwise recovering lithium and rare earth from rare earth molten salt electrolytic slag according to claim 1, wherein in the step (4), the mass ratio of the reducing agent to the acid leaching slag is 0.01-0.15:1, and the final acidity of the acid leaching process of the acid leaching slag is controlled to be 0.5mol/L.
10. The method for stepwise recovering lithium and rare earth from molten salt electrolyte slag of claim 1, wherein in the step (4), the reaction temperature of the acid leaching is 30 ℃ to 95 ℃ and the reaction time is 0.5h to 6h.
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